• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.11
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• pp.1621-1627
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• 2013

This paper compares power losses between voltage controlled before and after using power conversion device in AC feeding system. For this purpose we present voltage control procedures and criteria and model high speed line and train using PSCAD/EMTDC to compare power losses in various feeding condition. Power losses of the simulation result in power control before and after in single point feeding system was reduced maximum 0.37 MW(23.8 %) and average 0.23 MW(20.5 %) when one vehicle load operates maximum load condition. When three vehicles operate maximum load condition in one feeder section, power losses after voltage control was reduced 1.03 MW(49.5%) compared to before voltage control. And, power loss of parallel feeding system is reduced the average 0.08 MW(7.2 %) compared to the single feeding system. In conclusion, adaptive voltage control method using power conversion device can reduce power losses compared with existing method.

• Smart Structures and Systems
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• v.4 no.5
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• pp.685-696
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• 2008

This paper deals with the numerical model of a bracing-friction damper system and its deployment using the optimal slip load distribution for the seismic retrofitting of a damaged building. The Slotted Bolted Connection (SBC) type friction damper system was tested to investigate its energy dissipation characteristic. Test results coincided with the numerical ones using the conventional model of a bracing-friction damper system. The placement of this device was numerically explored to apply it to the assumed damaged-building and to evaluate its efficiency. It was found by distributing the slip load that minimizes the given performance indicies based on structural response. Numerical results for the damaged building retrofitted with this slip load distribution showed that the seismic design of the bracing-friction damper system under consideration is effective for the structural response reduction.

• Journal of Power System Engineering
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• v.18 no.5
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• pp.88-93
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• 2014

In this paper, the performance analysis of condensation and evaporation capacity, turbine work and efficiency of the OTEC power system using vapor-liquid Ejector is presented to offer the basic design data for the operating parameters of the system. The working fluid used in this system is $CO_2$. The operating parameters considered in this study include the vapor quality at heat exchanger outlet, pressure ratio of ejector and inlet pressure of low turbine, mass flow ratio of separator at condenser outlet. The main results were summarized as follows. The efficiency of the OTEC power cycle has an enormous effect on the mass flow ratio of separator at condenser outlet. With a thorough grasp of these effects, it is possible to design the OTEC power cycle proposed in this study.

• Advances in Traditional Medicine
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• v.7 no.5
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• pp.518-526
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• 2008

Recently a major goal in asthma therapy is to reduce or prevent the inflammatory response of airway. Eosinophilic accumulation in the tissue is a prominent feature of allergic diseases including asthma. Production of chemokines by bronchial epithelial cells may contribute to the allergic inflammation by recruiting eosinophils. In this study we evaluated the inhibitory effect of Gamichungsangbohatang (GMCSBHT), used traditionally in treating asthma, on secretion of chemokines for eosinophils in human A549 epithelial cells. Chemokines such as eotaxin, RANTES, IL-8 were inhibited in a dose-dependent manner, but IL-16 showed no inhibition by GMCSBHT. These findings indicate that GMCSBHT might be a therapeutic value in treating asthma by suppression of chemokines secretion associated with local accumulation of eosinophils.

• Journal of Korea Foundry Society
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• v.28 no.5
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• pp.226-230
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• 2008

본 논문에서는 공정조성 부근의 Al-Si 합금의 미세구조에 미치는 전자기교반(EMS)의 영향에 대하여 연구하였다. 초정 a 상의 형상에 미치는 전자기교반의 세기의 영향을 조사하기 위하여 각각 교반장치에 60, 80,및 120V의 전압을 가하여 미세조직을 관찰하였다. 60V 이하의 전압이 인가되었을 때 전자기교반의 효과가 나타나지 않은 반면에, 80V 이상의 전압으로 5초 이상 인가되었을 때 구상화된 초정 a 상을 얻을 수 있었다. 인가된 전압이 120V일 때 초정 a 상은 보다 균일한 분포를 가지며 구상화 되었다. 전자기교반의 세기와 함께 교반시간의 영향을 확인하기 위하여 교반시간을 증가시키면서 미세조직을 관찰하였다. 또한 초정 a 상의 형상에 미치는 주조변수의 영향에 대해서도 실험하였다.

• Journal of the Optical Society of Korea
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• v.8 no.4
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• pp.174-181
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• 2004

Various kinds of systems, that can do target recognition and position detection simultaneously by using infrared sensing detectors, have been developed. In this paper, the detection system TRSS (Thermal target Recognition by Spiral Scanning) adopts linear array shaped uncooled IR detector and uses spiral type fast scanning method for relative position detection of target objects, which radiate an IR region wavelength spectrum. It can detect thermal energy radiating from a 9 m-size target object as far as 200 m distance. And the maximum field of a detector is fully filled with the same size of target object at the minimum approaching distance 50 m. We investigate two types of lens systems. One is a singlet lens and the other is a doublet lens system. Every system includes one aspheric surface and free positioned aperture stop. Many designs of F/1.5 system with ${\pm}5.2^{\circ}$ field at the Efl=20, 30 mm conditions for single element and double elements lens system respectively are compared in their resolution performance [MTF] according to the aspheric surface and stop position changing on their optimization process. Optimum design is established including mechanical boundary conditions and manufacturing considerations.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.17 no.3
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• pp.1-11
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• 2014

Recently, major cities in Korea are suffering from frequent urban flooding caused by heavy rainfall. Such urban flooding mainly occurs due to the limited design capacity of the current drainage network, which increases the vulnerability of the cities to cope with intense precipitation events brought about by climate change. In other words, it can be interpreted that runoff exceeding the design capacity of the drainage network and increased impervious surfaces in the urban cities can overburden the current drainage system and cause floods. The study presents the green roof as a sustainable solution for this issue, and suggests the pre-design using the LID controls model in SWMM to establish more specific flood prevention system. In order to conduct the computer simulation in connection with Korean climate, the study used the measured precipitation data from Cheonan Station of Korea Meteorological Administration (KMA) and the forecasted precipitation data from RCP 8.5 scenario. As a result, Extensive Green Roof System reduced the peak runoff by 53.5% with the past storm events and by 54.9% with the future storm events. The runoff efficiency was decreased to 4% and 7%. This results can be understood that Extensive Green Roof System works effectively in reducing the peak runoff instead of reducing the total stormwater runoff.

• Applied Biological Chemistry
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• v.33 no.2
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• pp.125-128
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• 1990

Previous work has shown that the levels of free and total IAA and tryptophan decrease on exposing etiolated pea (Pisum sativum L. var. Sparkle) seedlings grown at $25^{\circ}C$ to $5^{\circ}C$ for 3 days, suggesting that low temperature down-regulates the level of endogenous IAA, in part, by reducing tryptophan biosynthesis. To understand, in this study, the effect of low temperature on the regulation of IAA degradation system in etiolated pea seedlings, enzyme levels of IAA degradation system and hydrogen peroxide content were analyzed during and after chilling($5^{\circ}C$) 6-day-old pea seedlings grown at $25^{\circ}C$. The levels of IAA oxidase and peroxidase increased during chilling and gradually restored to the level of control on termination of chilling. Catalase levels decreased upon chilling and increased to the level of control on termination of chilling. $H_2O_2$ was accumulated during chilling up to the level of $5.5\;{\mu}mol/g$ fresh weight while at $25^{\circ}C$ maintained a relatively constant $H_2O_2$ level of $4\;{\mu}mol/g$ FW. All together, it appears that low temperature, in part, by increasing enzyme levels of IAA degradation system and accumulating $H_2O_2$, down-regulates endogenous level of IAA in etiolated pea shoots.

• Bulletin of the Korean Chemical Society
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• v.30 no.7
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• pp.1505-1515
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• 2009

A new method to semicontinuously determine $PM_{2.5}$ ionic species with a short time resolution is described in detail. In this system, a particle collection section (mixing part, particle collection chamber, and air/liquid separator) was developed. A Y-type connector was used to mix steam and an air sample. The particle collection chamber was constructed in the form of a helix coil and was cooled by a water circulation system. Particle size growth occurred due to the high relative humidity and water absorbed particles were efficiently collected in it. Liquid samples were drained out with a short residence time (0.08-0.1 s). The air/liquid separator was also newly designed to operate efficiently when the flow rate of the air sample was 16.7 L $min^{-1}$. For better performance, the system was optimized for particle collection efficiency with various types of test aerosols such as ($NH_4)_2SO_4,\;NaCl,\;NH_4HSO_4,\;and\;NH_4NO_3$. The particle collection efficiencies were almost 100% at different concentration levels in the range over 500 nm in diameter but 50-90% in the range of 50-500 nm under the following experimental conditions: 15 coil turns, a water flow rate for steam generation of 0.65 mL $min^{-1}$, and an air sample flow rate of 16.7 L $min^{-1}$. Finally, for atmospheric applications, chemical compositions of $PM_{2.5}$ were determined with a time resolution of 20 min on January 11-24, 2006 in Seoul, Korea, and the chemical characteristics of $PM_{2.5}$ ions were investigated.

• Journal of Preventive Medicine and Public Health
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• v.10 no.1
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• pp.102-108
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• 1977

A study on the sickness distribution and mode of treatment in rural area was conducted during the period from July '75 to Aug. '75 using 1,225 households, 7,918 population (4,017 male, 3,901female) and 343 cases th at found during the period of survey who had beenlived in Nammyon, Hwasoongun, Chonnam. The summarized results were as follows : 1. Average family number per household was 6.5 and prevalence rate was 43.3 (21.2 for male, 22.1 for female). 2. General sickness distribution by classification of disease according to W.H.O. was highest in disease of the nervous system and sense organs (21.3%), and important others were disease of the digestive system (16.9%) and disease of the respiratory system(14.8%). In male, distribution was in order of downward disease of digestive system, disease of nervous system and sense organs, disease of skin, cellular tissue, bones and organs of movement, and disease of respiratory system. In female, distribution was in order of downward disease of nervou s system and sense organs, disease of respiratory system, disease of digestive system, and disease of skin, cellular tssue, bones and organs of movement. 5. Types of treatment in both sexes were showed that home and folkmedicine (41.1%), pharmacy(24.5%), admission to hospital or clinic (16.9%), out-patient clinic (10.8%) and herbmedicine (6.7%) in downward order. Hospital and clinic utility rate was 27.5% (31.5 for male, 24.0 for female) and it was highest in 0-4 age groups and lowest in 40-49 year age groups. 4. Hospital and clinic utility rate was highest in neoplasms, and the other hands, disease of the nervous system and sense organs and disease of the digestive system were the highest groups in the all types of treatment other than hospital and clinic. 5. On the results of treatment not, exactly replied answer was the highest (41.7%) and only 16.0% said complete recovery. In completely recovered cases, hospital and clinic using group was predominant (58.2%) and in aggravated cases, home and folkmedicine using group was highest.